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Questions tagged [rf]

Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.

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Analyzing and Improving Power Filtering

I have a wireless radio NRF24L01+ hooked up to a 3.3V LDO voltage regulator. The battery that powers the LDO also powers high current motors. The NRF24L01+ already has 100uF capacitors near the device ...
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90 views

RF Circuit: Groundplane on RF module/microcontroller side? [on hold]

I'm beginner about designing RF circuits... PCB has an RF module works at 433 MHz on the back side. On the top side has regulator and microcontroller pads for Arduino Pro Mini. Layout picture: ...
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1answer
41 views

diode identification help A7

I'm trying to figure out what this diode is. The marking indicates "A7" and also has "t36" stamped on it suggesting maybe a 1N4007 rectifier diode. However, when I test it with my multimeter I get a ...
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1answer
54 views

Itead Sonoff RF WiFi & 433MHz switch: Identifying an unknown chip on the 433MHz card

I have the Sonoff RF which is a mains relay switch which is activated by either WiFi or a 433MHz remote. The particular Sonoff RF's I have arrived from China on 21/9/2017. I flashed these Sonoff RF's ...
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25 views

i want to test a low pass filter using instrustar usb oscilloscope+multi viranalyser ? how to do it? [closed]

How to test a low pass filter using a virtual dual usb oscilloscope?i have tried but couldn't do it.
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1answer
46 views

How to design RF amplifier with dual emitter transistor

I have a bipolar dual emitter transistor BFP840(Infineon) and want to design a common base amplifier at 5GHz, but I don't know how to lay it out because a resistor is connected to its emitter. Should ...
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26 views

ESP32 with LNA and PA

I would like to add a low noise amplifier and a power amplifier to the ESP32. As you may know there is only one RF output on the chip. I was thinking of adding an RF switch, and switching between ...
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1answer
29 views

How to Model a Bias Tee in ADS

I'm modeling a Bias Tee in ADS and I wanted to ask how to add board parasitics into the model and what should the results of a good model look like in terms of the S-parameters. This is my first time ...
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30 views

RF Remote Cloning [closed]

I need to clone a RF remote. I think it works on 433MH. I used RC switch library for Arduino and it says it detected data from remote (protocol :5 ; bit length :24; time:511ms) But when I transmitted ...
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1answer
86 views

Power amplifier design

For my research purpose, I am planning to design one power amplifier (basically, a current amplifier) with the following specification- Frequency range: 0-100MHz (or at least 0-30MHz) Output voltage: ...
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0answers
20 views

How to find Q of a quarter-wave resonator loaded with a coupled-line coupler

I have a quarter wave resonator at frequency \$f_0\$ and characteristic impedance \$Z_{res}\$, which is coupled to a 50 Ohm load via a segment of coupled-lines coupler whose electrical length is \$\...
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50 views

What does a wireless chip do?

This is a basic question but it taken my time for a while since I do not have enough knowledge in this area. Recently, I am investigating about functionality of a wifi and bluetooth chip ...
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Parasitic Passbands in distributed filters

it is known that if we realize a filter (for instance a low pass filter) by using distributed elements (transmission lines), there will be some parasitic passbands (which moreover show a behaviour ...
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0answers
26 views

Identifying the appropriate RFID Module [closed]

Okay so, there is a RFID Tag chip that I would like to read and write. I searched a lot about it and I got some clues that should help answer this question. FX 160K95122 K1 HFD1-T MDK 338V-0 N I ...
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1answer
61 views

Identify this symbol: circle with arrow across

What could be the meaning of the circle with an arrow diagonally across it? I haven't seen this anywhere before.
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2answers
43 views

Impedance matching 2MHz clock 2m cable PCB to PCB

I am starting to design one of my first instances where I think impedance matching/ reflections might be an issue. I want to daisy chain a clock from four seperate PCBs with a distance between PCBs ...
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1answer
60 views

How do I detect what kinds of signal(s) this device receives/sends

Xcortech 3300w - Component board So I have a somewhat hopefully simple question. I'm a bit of an amateur with on-board components and am trying to figure out what kind of signals this board receives. ...
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1answer
39 views

SPST RF switching application with PIN diode

I need a single-pole single throw (SPST) RF switch. I have implemented the following circuit for 2.4 GHz, (PIN diodes in RF switch applications / Infineon) I obtained the following S11 results with ...
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2answers
34 views

Adjacent Signal Selectivity: Section 6.1 of ETSI EN 303 372-2 (RED testing). Bad procedure/standard?

I'm doing pre-certification testing to ETSI EN 303 372-2 V1.1.1 (2016-04), specifically the Adjacent Signal Selectivity test in Section 6.1. I am a Systems engineer with lots of experience designing ...
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2answers
125 views

HT12e: How is this a 2¹² encoder?

I am using HT12E, for a rf transmitter circuit. As per the datasheet HT12E is a 2¹² encoder. Ideally such an encoder must have 2¹² inputs and 12 outputs. In addition to that all the inputs should be ...
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3answers
186 views

How can I record RF?

For audio I can use just sound card, plus OS api to record any signal from 20 hz (below that's blocked via capacitor) to 96khz(that's half of max samplerate). But what if I just want to go higher? As ...
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1answer
34 views

Transmitter / Amplifier matching

I am trying to add an amplifier to a transceiver to increase the range but I am not sure how to add the reference schematics together (eg what components to remove, combine, etc). The top schematic ...
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0answers
24 views

Can XBEE S2C be used as Slip Radio? [closed]

The Goal I'm attempting to implement a Contiki/6LowPAN support on Raspberry Pi to transmit IPv6 packets through 6LoWPAN Border Router over Slip Radio. What I want to know I am working with XBEE S2C ...
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0answers
39 views

Are magnetically tunable surface acoustic wave devices commercially produced?

I have been reading up on studies of magnetically tunable surface acoustic wave devices, in general they note the relative velocity change or in some cases a frequency shift if it is part of an ...
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2answers
392 views

What does the wifi amplifier exactly amplify?

The question is not exactly about the wifi, but on how does this operate in full duplex, in principle? As an practical example, lets take some commercial amplifier. As we can see from the picture, it ...
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1answer
45 views

can aluminum foils increase the boost the range of nfc reader?

I have been working on a project where I have to read data from an NFC tag and store the information locally. Currently I have a range for the NFC tag of about 5 cm. The tags will be present inside a ...
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2answers
171 views

AM Radio Wave LED Indicator

I recently learned about simple AM transmitters and receivers. Now, I'm trying to apply this and expand my understanding by trying to create an AM radio wave powered LED. I'm a very beginner ...
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2answers
39 views

Is there any physical limitation to cell carries sharing the same frequency?

Currently in the U.S. certain companies are granted leases on certain frequencies for cell phone communication. I was discussing with a friend how this allows a company with a lower frequency to get a ...
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0answers
50 views

Has anyone designed a low noise amplifier in the ISM band (24 GHz) using the discrete fet CEL CE3520K3?

I have been trying to design an LNA in the 24 GHz ISM band using CE3520K3. The FET is inherently unstable and one cannot use resistor loading at the input, resistive loading at the output, source ...
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1answer
28 views

How to convert lumped components to TL segments?

I have the following circuit: which I need to implement in Microstrip. For now in order to get the correct results I was using lumped capacitors. But I will need to use Microstrip stubs when ...
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3answers
97 views

Why do carrier waves sound silent on radios?

I was recently reading about and building low-power AM radio transmitters, and read/noticed that when the carrier wave is not yet modulated, the radio receiver goes silent. For example, let's say my ...
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1answer
55 views

What is the major difference between a WiFi and RF Module?

In an interview recently, someone asked me what is the major hardware level difference between a WiFi module (ESP8266) and RF module (nRF24L01+) that I had used in my projects. I mentioned that both ...
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27 views

RFI protection for a stepper motor controller

I'm building a remote tuning device for a magnetic loop antenna. It will use a stepper motor to turn the shaft on the mag loop's variable capacitor. The electronics will consist primarily of a ...
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0answers
18 views

Unitary property of scattering matrix

From s-parameter lossless network definition , The sum of the incident powers at all ports is equal to the sum of the reflected powers at all ports. But how do we derive the above unitary property ...
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1answer
54 views

How to reduce the range of RF sensors to 1.5m? [duplicate]

I have bought four RF sensors from Robokits - Wireless RF serial link 433 MHz +20 dBm 2 Km range. I want to locate one of them with the help other three sensors by the means of triangulation. My ...
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2answers
112 views

Strange shapes on the Wi-Fi module PCB

LG has this Wi-Fi module: This is a 2X2 Dual Band AC Wi-Fi / BT module. You will see two folded WiFi antennas on upper side and one bluetooth PCB trace antenna at the lower right side. I found this ...
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38 views

Unexplained differences in behaviour between U.FL-terminated antenna and SMA-terminated antenna

I would like your opinions/advice regarding an unexplained observation between a U.FL-terminated antenna and an SMA-terminated antenna. Both antennas are from the same manufacturer and normally tuned ...
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4answers
1k views

Why do OOK transmissions have bandwidth?

With on-off keying, you have a single carrier wave at a constant frequency transmitting its presence or absence. Now I understand that the crystal will not be perfect so you will have some minimal ...
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3answers
82 views

BJT Amplifier vs Manufactured RF Mixers

900Mhz Operation This is a BJT mixer design I found on google From my understanding in order to use a BJT amplifier as a mixer you have to be in the 1dB compression point. Question: Am I wrong ? ...
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1answer
52 views

Does a lithium battery make a good ground plane?

A patch antenna I'm using calls for a 50mm x 50mm ground plane under it, mostly to cut multipath reflections in the bottom lobe. Naturally, the closer to the antenna and the more conductive the ground ...
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1answer
149 views

How do I correctly protect my MCU from resetting during a current surge on RF transmission?

I designed a PCB with a SIM868 module for data transmission. On the PCB, the MCU resets randomly on transmission start of the SIM module. On a breadboard setup, it worked just fine, even without caps. ...
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0answers
22 views

Power spectral bandwidth interpretation

I'm developing a LoRa solution that I want to check is compliant with radio spectrum laws in Australia. The radio will transmit at 915Mhz at 22dBm (158mW) with a channel bandwidth of 500Khz, and won't ...
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3answers
58 views

Does data rate increase with channel frequency?

It is commonly said that a higher channel frequency implies a higher data rate. For example, in https://www.howtogeek.com/222249/whats-the-difference-between-2.4-ghz-and-5-ghz-wi-fi-and-which-should-...
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2answers
50 views

Resources on Noise Circuits

Back when I was taking an RFIC design course, I was pretty disappointed by the noise part of the class, specifically calculating the output-referred noise voltage, noise figure of an amplifier, etc. ...
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2answers
44 views

Determining whether signal meets the 12 dB SINAD voltage

The specification for the sensitivity of a certain radio receiver says: Typically 12dB SINAD NBFM for 0.15uV at 145MHz. If I understand correctly, this means that the received radio wave should have a ...
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0answers
19 views

ESP32: Using SENSOR_VP as GPIO

According to the ESP32 Hardware Design Guidelines, in section 2.1.6, they said: If SENSOR_VP and SENSOR_VN are used as GPIOs, while ADC is supported by other pins in the circuit design, users ...
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1answer
93 views

What are the main characteristics of high reactive power RF capacitors?

This question is related to this one. I have to design a high quality factor RF parallel resonant circuit, to be placed in parallel to the output of a medium to high power RF generator. Precisely, ...
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1answer
37 views

What are the units when solving Transmission Line iterativelly?

I would like to know the conductancee,\$C\$, and capacitance,\$G\$, of my lossy transmission line which is configured as an open circuit. In such a case, I know that the expression that defines the ...
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2answers
80 views

Reducing the range of a D flip-flop frequency detector

I'm designing a frequency tracking circuit and I came up with a circuit that tracks frequencies from Fclk to Fclk/2: However, it would be very nice if the bandwidth was a bit narrower, from Fclk to ...
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1answer
48 views

Can we install product above FCC test power level declared in certification report

we have a product which has radio of 1W maximum output power , we have sent product for FCC through party lab, and they certified the product with 18 dbm only. So we get the certificate with only 18 ...